Telephone system.



H. W. MUNSELL.

TELEPHONE SYSTEM.

APPLICATION FILED JUNE28, I909.

1,150,055. I Patented Aug. 17, 1915.

IRA!

III'IIIIIIIHIII UNITED STATES PATENT oFF on.

HARRY w. MUNSELL, or INDIANAPOLIS, INDIANA, ASSIGNOR T0 xnnnoee swrron-v BOARD & SUPPLY COMPANY, A CORPORATION or ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent. Patented Aug. 17,1915.

Application filed June 28, 1909, Serial No. 504,762,

larly to the circuits and apparatus for applying ringing current to the called-for line to signalthe called-for party. In systems of this sort, the connection of a link-circuit to the called line for the purpose of completing the connection from the. calling line to the called line is followed by the application of ringing current to actuate the bell of the called party, and such current islapplied either continuously or intermittently until the called party responds to the call, whereupon the source of current is disconnected from the line. In these systems, the

application of ringing current may require.

the operation of a ringing key, or may be brought about by the mere insertion of the connecting plug into the jack ofthe called- :for line. In the form of-my invention herein disclosed, this latter method of operation is employed.

The principal object of the present invention is to provide a novel arrangement of the character indicated, which shallbe positive in operation and economical to manufactureby reason of its simplicityand fewness of parts.

3 In carrying out my invention, I preferably employ a link-circuit which may be either a cord-circuit or a t'runk-circi'lit, having five principal relays; one a ringing or ,flip flop relay for connecting the ringing source in circuit; a second controlled from the-calling line end of the circuit; a'third actuated upon-connecting the opposite end of the link-circuit to the called-for line;-a

scope of the invention will be more particularly pointed out in the appended claims.

In the drawing, I have illustrated, in I diagram, a telephone system having a trunkcircuit constructed and arranged acfidrding to my invention. Although thus ,i

trated, it will be apparent that my invention' is applicable to cord-circuits as well as trunk-circuits. In this diagram, A and B designate substation circuits of calling and called lines, respectively, which extend by limbs 1, 2 to dilferent exchanges, where they are provided with suitable multiple acks 3. At one exchange, a link-circuit C, of well known construction, is employed. this circuit, the tip and sleeve strands 514, 5 terminate at the left in tip and sleeve; contacts of the answering plug 6, and atthe right in tip and sleeve contacts of the connecting plug 7. Trunk conductors 8 and 9 extend between the exchanges- These conductors their incoming ends in the windings ll and I 12 of a repeating coil whose companion windings 13, 14 are connected to the tip and sleeve trunk strands 15 and 16 whichi'terminate in tip and sleeve contacts of connecting plug 17, which is adapted to be insertedinto a multiple jack 3 of the called liner It-i's with this latter section of the trunk-circuit thatthe novel ringing circuits are associated. It will be understood that thediagram illustrates the apparatus and circuits .which are brought into play in establishin" a conversational circuit. from substation a calling substation, to substation B as the called substation. Inestablishing this connection, the operator, having control of the cord-circuit C, is known as the A oporator, while that operatm" in the distant exchange, having control of the connecting plug 17, is known as the B operator, This general arrangement of trunking between exchanges is old in the art and forms no part of my invention.

Each substation is provided with the usual transmitter 18, receiver-19, switch book 20, condenser 21, and ringer 22'. When the parts are in normal position, a path for alternating current is supplied througheom denser 21 and ringer 22to actuate the latter, and when the receiver'is off its book, an alternate path for battery currentis providedthrough transmitter 18 and receiver 19. At

each exchange, line limb 1 is normally connected through contacts of a cut-off relay 23 to the grounded pole of the battery 24, and the line limb 2 is normally connected to the opposite pole of said battery through contacts of the cut-off relay 23 and the winding of line relay 25, which controls line lamp 26.

In the cord-circuit, strands 4 and 5 are, as usual, conductively divided by condensers 27 and 28 and are provided with tip and sleeve answering supervisory relays 29, 30, calling tip and sleeve supervisory relays 31, 32, test relay 33, operators set 34, listening key'levers 35, 36, and ringing key levers 37 38. Relays 29 and 30 jointly control the answering supervisory lamp 39, and relays 31, 32 the calling supervisory lamp 40, while the ringingkey is adapted to connect the generator 41 in circuit with a called line whenever said cord-circuit is used in con necting-directly to a called line instead of to the trunk-circuit, such as illustrated in the diagram. WVhen connection. is made to the'latter, the ringing key and associated generator are not used. In the trunk-circuit, the sleeve strand 9 is connected to the grounded pole of the battery through impedance coil 42. At the opposite end of this strand, a trunk relay TK is included in a branch normally connected to the grounded pole of the battery via contact 43 of tip relay TR. A similar branch extends. from the corresponding end of the trunk conductor 8 to a normally open contact of relay TR. Condensers 44 and 45 conductively separate the windings 11, 12 and 13, 14 of the repeating coil. Tip relay TR is con nected between the grounded pole of battery 46 and tip strand 15, and a sleeve relay SR is similarly connected between the opposite pole of said battery and thesleeve strand 16 of the trunk-circuit. A ringing or flip-flop relay RG controls the continuity of the strands 15, 16 and the application of ringing currentfrom the generator 47, while a release relay RR cooperates with the other relays of the circuit in discontinuing the application of the ringing current. A test relay 48 and a pilot relay 49 are also provided. Transmission is obtained between the A and B operators through theorder-wire circuit 50, which connects the B opera-tors set 51 with the A operators set 34 through the agency of a key 52 under the control of the A operator. The test relay 48, as usual. controls the circuit through the tertiary winding of the induction coil of the operators set. Now, if it be assumed that a party at substation A desires to converse with a party at substation B, the former will remove his receiver 20 from its hook and thereby en ergize his line relay 25 to light line lamp the called-for party 26 as a signal to the operator that a call is being made. The operator will respond by inserting answering plug 6 into answering jack 3 of that line and thereby actuate cutoff relay 23 to extend the limbs 1, 2 to the jackterminals and to disconnect the line relay 25. This act will also energize super visory relays 29 and 30, the former over the line circuit, and the latter through the cutoff relay and over the line circuit in parallel, as is well known. By depressing listening key levers 35, 36, the A operator will learn that connection is desired with a subscriber whose line terminates at the distant exchange. She will then actuate her key 52 to bring the B operators set 51 into circuit with her set 34 and receive, from her, instructions as to the trunk to be used in making the connection. Upon this assignment of a trunk, the A operator will immediately insert the connecting plug 7 into a jack 10 of the assigned trunk. This act energizes supervisory relay 32 and trunk relay TK. The circuit by which this is accomplished extends from the live pole of battery 24, through relay 32, sleeve strand 5, plug and jack sleeve contacts and impedance coil 42 to the return side of the battery; another path of current extending from the sleeve contact of the jack, over conductor), through repeating coil winding 12, trunk relay TK, and normal contact 43 to the grounded side of the battery. As a result of the operation of relay 32, supervisory lamp 40 willbe lighted and, as will be seen hereinafter, remains lighted until his receiver from its hook. The actuation of trunk relay TK opens contact 53 and thereby opens the path through trunk lamp 54 and pilot relay 49. The operation of this relay also closes its contact 55 and thereby completes aportion of thecircuit for ringing relay RG, through interrupter 56, to the grounded pole of the battery. As soon as the B operator has designated the trunk for the first operator to plug into, she at once tests the line of the called party by touching the tip contact of plug 17 against a test jack contact of the wanted line and, in case the same is busy, obtains a circuit through test relay 48 which produces the customary click in her receiver indication that the line is busy. In such event, the calling party is so advised through the A operator. If, however, the wanted line is found to. be idle, then the B operator will insert plug 17 into a multiple jack 3 of the line running to substation B. The establishment of this connection energizes the sleeve relay SR and the cut-off relay 23 ot the called line over a circuit extending from the live pole of battery 46, through-relay SR, sleeve strand 16, plug and jack sleeve contacts and relay 23 responds by removing 11S Il to the return side of the battery. The operation of the latter relay, as before explained, extends the line limbs tolthe jack a test relay -18 and unites portions of the tip strand 15 and, by its contact 58, completes the circuit through the ringing. relay RG. This circuit, completely traced, extends from the live pole of the battery 46, through relay SR, closed contacts 58, 59, relay RU, closed contact 55, and interrupter 56 to the opposite pole of the battery. The closing of contact 60 of relay SR at this time performs no useful function. The energization of relay RG, however, interrupts the strands 15 and 16 at normal contacts 61, 62, and connects the ringing generator 46 in circuit. The presence of the interrupter 56 in the circuit of relay RG causes it to inter.- mittently connect the ringing generator in circuit. During the ringing interval, the ringing circuit may be traced from the live pole of the grounded generator 47, through alternate contact 61, plug and jack tip contacts, line limb 1, switch-hook 20, condenser 21, ringer 22, line limb 2, jack and plug sleeve contacts, alternate contact 62, protective resistance 63, and thence to ground through the battery 46. During this ringing interval, the circuit through the sleeve relay SR and cut-off relay 23 is interrupted, but current'is supplied for the latter relay througl'i protectiveresistance 63 and the alternate contact 62 of relay RU. Likewise,

sleeve relay SR is maintained energized by reason of the circuit through its winding and that of relay RG. before traced. Dur ing the nona'ingi nginterval, the sleeve side of the circuit is connected to the live pole of the battery through the winding of relay SR, while the tip side is connected to the opposite pole of the battery through the winding of tip relay TR. As a result of this, the removal of the receiver at substation B causes the operation of tip relay TR, the circuit for the latter being completed duringthe non-ringing interval from the live pole of battery 46, through relay SR, to the sleeve side of the circuit, thence through the substation transmitter and receiver to the tip side of the circuit, and finally through tip relay TR to the o 'iposite pole of the battery. The operation of relay TR destroysthe initial energizing circuit for trunk relay TK, but provides another which is also instrumental in operating tip relay 31 of the cord-circuit C of operator A, as an indication to her that the called party has responded. This circuit extends through the sleeve relay of cord-circuit C, and trunk relay TK, as before traced, and thence. instead ofto ground through normal contact 43, through alternate contact 13, re-

peating coil winding 11, trunk conductor 8, ack and plug tip contacts, strand 4, and finally through tip relay 31 to theop'posite pole of the'battery. Since tip relay TR controls tip relay 31 in this connection, it will'be seen that as soon as the called party at the end of conversation restores his receiver, tip relay 31 will be deenergizjed' and lamp l0 lighted. Similarly, the restoration of the receiver at si'ibstation A will cause Sll1 .)01'\lSUly lamp 339 to light, and upon the establishment of this condition, operatm' A will take down the connection. But to return to the operation of tip relay TR, it will be found that said relay discontinue the application of ringing current by operating release relay RR. The closing of contact 64 of relay TR completes a circuit for relay RR, and the latter is locked up over a circuit extending through closed contact 60 of relay SR, and closed contact 65 of relay RR. The operation of relay RR opens contact 59 and thereby deenergizes relay RG, thus disconnecting the generator 47 and maintaining the strands 15 and 16 continuous. In this condition, conversation may be carried on between stations A and B over the heavily marked circuit. Transmission current will be supplied to the transmitter at station A from-battery 24, through sleeve relay 30 to the sleeve side of the circuit, and from the same battery, through tip relay 29, to the tip side of the circuit. Similarly, transmissioncurrent will be supplied to the transn'iitter at substation R from battery 46, through sleeve relay SR to the sleeve side of the circuit, and from the same battery, through tip relay TR, to the tip side of the circuit. At the end of conversation, the restoration of the receivers to their hooks at stations A and B will cause the lighting of supervisory lamps 39 and 40 before the A operator, as just explained, and she will remove the plugs 6 and 7 fronrjaclts 3 and 10, respectively. As a result, cut-off relay 23 of the calling line will be deenergized and the circircuit and the circuit of the calledline will assume their normal conditions, thus leaving all the parts of the. apparatus at normal and ready for another connection.

It will be apparent that in carrying out my invention, certain alterations and modifications may be made in the a 'iparatus and circuits without departing from the Spirit and scope of my invention. I therefore do not wish to be limited to the specific matter illustrated, but aim to cover, by the terms of the appended claims, all such alterations and modifications.

What I claim as new and desire to secure by Letters Patent of the United States is uniting the opposite ends of the link circuit,

a pair of relays for controlling the circuit of said former relay, a control circuit for one relay of said pair extending to one end of said link-circuit, a control circuit for the other relay of said pair extending to the other end of said link-circuit, and switching mechanism station of said called line for rendering the circuit of the first said relay ineffective.

2. A telephone system comprising telephone lines, a link-circuit for use in establishing a conversational circuit between a calling line and a called line, a source of ringing current, a relay for controlling the connection of said source to the called line, a pair of relays for controlling the circuit of said former relay, a control circuit for one relay of said pair operated upon making connection with one end of said link-circuit, and a control circuit for the other relay of said pair operated upon making connection with the other end of said link-circuit.

A telephone system comprising telephone lines, a link-circuit for use in establishing a conversational circuit between a calling line and a called line, a source of ringing current, a relay vfor controlling the connection of said source to the called line and conductively disuniting the opposite ends of the link circuit, a pair of relays for controlling the circuit of said former relay, a control circuit for one relay of said pair including a portion of the talking circuit extending to one end of said link-circuit, a control circuit for the other relay of said pair includinga portion of the talking circuit extending to the other end of said lin-kcircuit, and switching means controllable at the called line for rendering one of said control circuits effective, said switching means being free from ground connection.

4. A telephone system comprising a telephone line, a link-circuit for establishing connection to said line, a pair of talking conductors uniting the ends of said link circuit, a source of ringing current, a first relay for controlling the connection of said source to said line, a second relay and a third relay each connected to astrand of said link-circuit, a circuit for actuating said second relay upon establishing connection to relays,

free from ground at the subsaid line, a circuit for actuating said third relay upon the response of the called party, a circuit for actuating said first relay, a fourth relay for opening said latter circuit upon the operation of said third relay, and

a locking circuit for said fourth relay controlled by said second relay.

5. A telephone system comprising a telephone line; a link-circuit for establishing connection to said line having five control relays, a first relay controlled from the calling end of the link-circuit, a second relay operated upon the connection of said linkcircuit to said line, a third relay actuated upon the operation of said first and second a fourth relay actuated upon the response of the called party, and a fifth relay actuated upon the operation of said fourth relay to decnergizc said third relay, a source of ringing current, and connections from said source to said connected line controlled by said third relay.

6. A telephone system comprising a tele-' phone line; a link-circuit for establishing connection to said line having five control relays, a first relay controlled from the calling end of the link-circuit, a second relay operated upon the connection of said linkcircuit to said line, a third relay actuated upon the operation of said first and second relays, a fourth relay actuated upon the response of the called party, and a fifth relay actuated upon the operation of said fourth rcla y to deenergize said third relay, a source of ringing current, connections from said source to-said connected line controlled by said third relay, and a, signal controlled by said first and second relays.

7. A telephone system. comprising telephone lines, a link-circuit for use in establishing connection between'said lines, a relay actuated in response to a control exercised at the calling end of said link-circuit, a second relay actuated in response to a control exercised at the called end of said linkcircuit, a circuit closed through contacts of said relays, a. source of ringing current, means for connecting said source to the called line in response to the closing of said latter circuit, and switching means free from. ground connection actuated upon the response of the called subscriber to disconnect said source.

8. A telephone system comprising telephone lines, a link-circuit for use in establishing connection between said lines, a relay actuated in response to a control exercised at the calling end of said link-circuit, a. second relay actuated in response to'a control exercised at the called end of said linkcircuit, a third relay actuated in response to a control exercised at the connected called station, a circuit closed through contacts of said first and second relays, and means for applying ringing current to the called line cuit and for disconnecting said application in response to the operation of said third,

relay.

9. A. telephone system comprising telepl'iouclincs, a link-circuit for use in estaln lishiug connection between said lines, a. relay actuated in response to the establishment of connection with the calling end of said link-circuit, a second relay actuated in response to the establishment of connection at the called end of said link-circuit, a circuit closed through contacts of said relays, a source of ringing current, and means for connecting said source to the called line in response to the closing of said latter circuit.

10. A telephone system comprising telephone lines, a link-circuit for use in establishing connection betweensaid lines, a relay actuated in response to the establishment of connection with, the calling endof said link-circuit, a second relay actuated in response to the establishment of connection at the called end of said link-circuit, a. third relay actuated upon response of the called party, a circuit closed through contacts of said first and secondrelays, and means for applying ringing current to the called line in response to the closing of said latter-circuit and for discontinuing said ap lication in response to tlieo 'ierationof said third relay. a

11. A telephone system comprising a telc-, phone line, a link-circuit for connecting to said line, a source of ringing current, a relay for controlling the connection of said source to'said connected line, and a second relay operative in response to the connection of said link-circuit to saidline to close a path-through both said relays.

12. A telephonesystem comprising a. telephone line, a link-circuit for connecting to said line, a source of ringing current, a relay for controlling the connection of said source to said connectedlinc, a second relay operative in response to the connection of said link-circuit to said line'to close a path through both said relays, and a third relay for completing the circuit through said latter relays.

13. A telephone system comprising a telephone line, a line relay and a cut-ofi' relay therefor, a link-circuit forconnecting to said line, asource of ringing current, a 'relay for controlling the connection of said source to said connected line, a second relay, a circuit closed through said second relay and said cut-off relay upon the connection of said link-circuit to said line, and a branch path through said control relay in parallel to that through said cutrofl' relay controlled in part by said second relay.

14.- A telephone system comprising a telephone line, a line relay and a cut-off relay therefor, a link-circuit for connecting to said line, a source of ringing current, a relay for controlling the connection of said source to said connected line, a second relay,

a circuit closed through said second relay and said cut-ofl relay upon the connection of said link-circuit to said line, a third relay, and a branch path through said control relay in parallelto that through said cut-oil relay controlled by said second and third relays jointly. v

In witness whereof, I hereunto subscribe my name this 24th day of June, 1909.

HARRY W. MUNSELL.

Witnesses CHARLES H. Barr er, CHESTER F. BAILEY. 

